DU 106: Denim Dictionary
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By Eric Steffen
Founder / Maker
FITTED Underground
Raw denim has a language. Part technical, part historical, part community slang — some of it Japanese, some of it borrowed from tailoring, some of it invented on internet forums by people who care far too much about indigo. This dictionary is an attempt to gather all of it in one place and define it clearly, without condescension and without gatekeeping.
You don't need to memorize this before buying your first pair. But it's here when you need it. The terms defined here appear throughout Denim University and throughout the broader raw denim community. Where a term has a full DU article devoted to it, I've included a link. The dictionary defines; the articles explain.
This dictionary is a living document. Terms will be added and definitions refined. If you have a suggestion or we've omitted something, please get in touch!
A B C D F G H I J K L M N O P R S T U W Y
A
Aizome — (藍染) Japanese term for indigo dyeing. A textile tradition that arrived in Japan from China around the fifth century CE and developed over a millennium into one of the most refined dyeing practices in the world. The aesthetic and technical foundation of modern Japanese selvedge denim. → See DU 004: How Japan Saved Raw Denim
Anti-skewing — A finishing process applied at the mill to offset the natural torque built into a denim twill weave. Without it, the legs of a pair of jeans will rotate toward the front after washing. Anti-skewing rotates the fabric slightly in the opposite direction of the twist before finishing, counteracting the effect. Applied to most sanforized denim as standard.
Arcuate stitching — The decorative arc stitching on the back pockets of jeans. Added by Jacob Davis in 1873 to distinguish Levi's from imitators, making it the oldest apparel trademark still in continuous use in the world. Every brand has its own version — a double arc, a single line, a more complex pattern, or nothing at all, which is its own kind of statement. On raw denim, the arcuate develops its own fading character as thread wears differently from surrounding fabric. → See DU 105: The Build
Atari — (当たり) Japanese term for the fading that develops along raised seams, edges, and high points of the garment — belt loops, pocket seams, the outseam, the hem. From the Japanese word for "hit" or "contact." Atari is typically the first fading to appear on a new pair and the most visible early indicator that a jean has been genuinely worn rather than artificially distressed.
B
Back rise — The distance from the top of the waistband to the crotch seam measured along the back of the jean. Determines how much coverage and room there is in the seat. Higher back rise means more room and comfort across a range of movement. Lower back rise produces a tighter, more fashion-forward seat that requires more precise fit through the thighs.
Bartack — A dense cluster of reinforcing stitches applied at stress points in a garment — belt loop attachments, pocket corners, the base of the fly. The difference between workwear construction and fashion construction, invisible when it's doing its job and immediately obvious when it isn't. → See DU 105: The Build
Beater — Community slang for a pair of jeans designated for hard, dirty, or demanding use — camping, construction, anything where you're not precious about damage. The beater is the pair you wear when you don't want to worry about your good pair. Every serious denim wardrobe has one.
Bleed / crocking — The transfer of excess surface indigo from new raw denim onto other surfaces — light-colored clothing, leather, furniture, skin. Most pronounced when the denim is wet or new. Diminishes significantly after the first few washes. Worth knowing about before you sit on a light-colored couch in a fresh pair.
Blowout — A hole or tear in the fabric at a point of extreme stress — most commonly the crotch, but also the knees and back pocket corners. A natural consequence of hard wear, particularly on denim that has gone unwashed long enough for the fabric to become brittle. Not a sign of poor quality — a sign of hard living. Can and should be repaired with darning, sashiko stitching, or a patch. Every blowout is an opportunity to add another chapter to the garment's story. → See Sashiko, Darning
Boro — (ぼろ) Japanese for "rags" or "tattered." A traditional Japanese textile philosophy in which worn or damaged fabric is reinforced and extended through layers of additional cloth, typically in indigo or natural tones. In raw denim culture, boro repairs are considered aesthetically valuable rather than shameful — the repair becomes part of the garment's history. → See Sashiko
Break-in — The process by which raw denim softens, stretches, and conforms to the body through wear. Break-in period varies significantly by weight — a 12oz pair may feel comfortable within weeks, while a 21oz pair may take several months. The break-in is not a hardship to be endured. It is the beginning of the relationship between the garment and the person wearing it.
C
Chain stitch — A stitch type using a single continuous thread looped back on itself, rather than the two-thread interlock of a standard lock stitch. Produces a characteristic roping and puckering effect as the fabric ages and washes. Used on quality raw denim hems and center back seams. Requires a specialized machine — a Union Special or equivalent. The roping at the hem of a well-worn pair of chain-stitched jeans cannot be replicated by a lock stitch. → See DU 105: The Build
Chevrons — The diagonal fade lines that develop on the inner thighs just above the inseam, formed by the fabric stretching and compressing during walking and squatting. Named for their V-shaped pattern. Less discussed than whiskers or honeycombs but a reliable marker of genuine long-term wear.
Contest pair — A pair of raw denim entered into a formal fade competition such as the Indigo Invitational. Typically started unworn on a specific date and worn consistently for the duration of the contest. Raw proof is required at the start. → See Indigo Invitational, Raw proof
Contrast — The visual difference between the faded and unfaded areas of a pair of worn jeans. High contrast means dramatic, distinct fade lines — near-white at the peaks, dark blue in the valleys. High contrast is the goal for most raw denim enthusiasts and is associated with heavier fabric, infrequent washing, and deliberate wear habits. → See DU 104: Denim Weight Explained
Cop — Community slang for a purchase. "Did you cop those?" means "Did you buy those?" Borrowed from broader sneaker and streetwear culture into the denim community.
Cotton twill — The weave structure that defines denim. A 3×1 right-hand twill means three warp threads pass over one weft thread in a repeating diagonal pattern, offset by one thread per row, producing the characteristic diagonal rib visible on any pair of jeans. The warp carries the indigo; the weft is typically undyed white cotton. Denim is defined as 3×1 twill — fabrics below 10.5oz typically use a 2×1 weave instead. → See 3×1 Twill, Warp, Weft
Crotch point — The single junction where the inseam, crotch seam, and seat seam all converge. The highest-stress point in the entire garment — the place where more directional forces act simultaneously than anywhere else in the jean. Quality construction reinforces this point with a bartack or gusset. Also where blowouts most often originate. → See DU 105: The Build
D
Darning — A textile repair method in which a grid of thread is woven across a hole or thinned area to reinforce or close it. The oldest and most traditional repair for blowouts. Can be done by hand or on a specialized darning machine. When done well, darning extends the life of a garment significantly without requiring a patch.
Deadstock — Fabric or garments that were produced and stored but never sold or worn, often for decades. Deadstock denim — particularly vintage Levi's, Lee, or Wrangler from the 1950s–1970s — is highly sought by collectors for its historical fabric characteristics, which cannot be replicated in contemporary production.
Denimhead — A dedicated enthusiast of raw denim, selvedge fabric, and the broader culture surrounding them. Self-applied and generally used with affection. The community has a reputation for obsessiveness — tracking wear counts, photographing fade progress, debating the correct number of months between soaks. There are worse things to be passionate about.
Dry — Another term for unwashed raw denim. "Keeping them dry" means refraining from washing to encourage higher-contrast fades. A contested practice — some enthusiasts go months or years without washing; others argue this simply shortens the life of the garment without meaningfully improving fades. Both positions have merit. → See Contrast, Wash
Dry denim — Another term for raw denim. Refers specifically to the unwashed state of the fabric. Used interchangeably with "raw" in the community and on product pages. → See DU 101: What is Raw Denim?
F
Fade — The gradual loss of indigo from the surface of denim through wear, washing, and abrasion. Not uniform — fades accumulate in patterns specific to the wearer's body, movement, and habits, making each pair of worn raw denim unique. The fade is the record. It is also the reason raw denim exists as a category. → See DU 101: What is Raw Denim?
Fade contest — A structured community competition in which participants begin a new pair of raw denim on the same date and compare fades after a set period — typically six months to a year. The Indigo Invitational is the largest ongoing fade competition in the world. → See Indigo Invitational
Felled seam — A seam construction in which the raw edges of the fabric are folded over and enclosed, creating a flat, durable finish on both sides. The standard seam for quality jeans construction. Produces the characteristic raised seam ridge visible on the inside of the leg.
FIFO (First In, First Out) — The practice of rotating through multiple pairs of jeans rather than wearing one pair exclusively, allowing each pair time to rest between wears. Less common among committed fade enthusiasts who prefer daily wear of a single pair for maximum fade development.
Five-pocket — The standard configuration of most jeans: two front pockets, one coin pocket set inside the right front pocket, and two back pockets. The design established in Jacob Davis and Levi Strauss's original 1873 patent and essentially unchanged since.
Front rise — The distance from the top of the waistband to the crotch seam measured along the front of the jean. Determines how high the jean sits on the body. Traditional raw denim typically runs higher in the rise than contemporary fashion denim. → See DU 105: The Build
G
Grail — A pair of jeans or a piece of denim that a collector actively seeks but hasn't been able to find or afford. Often a vintage or discontinued piece — a particular Levi's LVC run, a specific Iron Heart fabric, a deadstock find. The grail is aspirational almost by definition. Finding it is simultaneously satisfying and destabilizing, because then you need a new grail.
Griège — (Pronounced "grehj") A French textile term for raw, unfinished fiber or fabric as it comes off the loom. In denim specifically, it refers to the fine surface hairs that cover loom state fabric before any processing. Sanforization singes these hairs away; unsanforized kibata retains them, contributing to the characteristic hairiness and texture of loom state fabric. → See DU 103: Sanforized vs. Shrink to Fit
H
Hang dry — The standard drying method for raw denim after washing — hung by the waistband or laid flat rather than placed in a machine dryer. Preserves fabric structure, prevents excessive heat-induced shrinkage, and avoids the mechanical stress that tumble drying inflicts on heavy denim. The right call for any pair you care about.
Heritage — A broad descriptor for clothing brands, styles, and garments rooted in American and Japanese workwear traditions — denim, selvedge, natural materials, traditional construction. Raw denim sits firmly within heritage culture. The word can drift toward marketing language; the more meaningful signal is whether the construction and materials actually reflect the tradition being claimed.
Hige — (ヒゲ) Japanese for "whiskers." Used interchangeably with "whiskers" in the raw denim community, particularly when referencing Japanese brands and fade culture. → See Whiskers
Honeycombs — The repeating geometric fade pattern that develops behind the knees as the fabric compresses and decompresses over months and years of wear. Named for their visual resemblance to a honeycomb. Among the most sought-after fades in the raw denim community — proof of genuine long-term wear that cannot be convincingly faked.
I
Indigo — The dye that makes blue jeans blue. Unique among dyes in that it bonds only to the outer surface of the cotton yarn rather than penetrating to the core — producing the ring-dye effect that makes raw denim fades possible. Almost all commercial indigo today is synthetic, developed by BASF in Germany and introduced commercially in 1897. Natural indigo from plant sources is rarer and more expensive, and carries a tradition stretching back thousands of years across India, West Africa, Japan, and the Americas. → See DU 001: Indigo Around the World, DU 101: What is Raw Denim?
Indigo Invitational — The world's largest raw denim fading competition, running annually since 2019. Participants begin a pair of unworn raw denim on January 1 and submit fade documentation at year end for community judging. Has grown into a genuinely global event spanning multiple regional brackets.
Inseam — The seam running from the crotch point to the hem along the inside of the leg. Also the measurement used for leg length. On quality raw jeans, typically chain-stitched. On unsanforized denim, the inseam should be cut at least two inches longer than needed to account for shrinkage on first soak. → See DU 105: The Build, DU 103
J
J-pocket — The classic workwear front pocket construction, named for its curved shape. A single piece of fabric cut in a continuous arc from the waistband into the side seam, producing a deep, functional pocket with a clean finished curve. The traditional choice for raw denim five-pocket jeans. → See DU 105: The Build
K
Kaizen — (改善) Japanese business and manufacturing philosophy meaning "continuous improvement." The idea that no process is ever finished — that there is always something to refine, understand more completely, or do better. One of the foundational philosophies behind Japanese denim culture, in which each production run is treated as an opportunity to learn something the previous one hadn't taught. → See DU 004: How Japan Saved Raw Denim
Kibata — (キバタ) Japanese term for unsanforized, loom state denim. Widely used in the raw denim community to refer to shrink-to-fit fabric, particularly of Japanese origin. If a pair of jeans is described as kibata, expect 7–10% shrinkage on first soak. → See DU 103: Sanforized vs. Shrink to Fit
L
Left-hand twill (LHT) — A denim weave in which the diagonal rib runs from top right to bottom left — the opposite of the standard right-hand twill. Left-hand twill tends to fade differently, often with softer, less dramatic contrast, and has a slightly different hand feel. Cone Mills' White Oak plant produced a notable LHT selvedge before closing in 2017.
Leg twist — The tendency of unsanforized denim to rotate at the leg after washing, caused by the natural torque built into the twill weave. The inseam gradually migrates toward the front of the leg. Some enthusiasts love it for its historical authenticity. Others find it uncomfortable. Anti-skewing prevents it. → See Anti-skewing
Ligne — (Pronounced "leen") A unit of measurement from the French watchmaking and button trade, used to specify button diameter. One ligne equals 1/12 of a French inch, or approximately 0.635mm. To convert: multiply the ligne number by 0.635 to get millimeters. A 20–24 ligne button (roughly 13–15mm) is typical for a raw denim waistband; a 27 ligne button (approximately 17mm) reads as more substantial and workwear-influenced. The system dates to pre-metric France, where it was adopted by the button industry — particularly in Paris, the center of European button manufacturing from the 17th century onward. Still in use in menswear, bespoke tailoring, and the button trade despite the broader adoption of metric measurement.
Living document — The governing metaphor of raw denim: a pair of jeans understood as a record of the wearer's life, with fades, repairs, wear marks, and patina accumulating over time into a unique object that tells a specific story and belongs entirely to the person who wore it. No two pairs age the same way.
Lock stitch — The standard machine stitch used in most garment construction, formed by two threads interlocking through the fabric. Strong and consistent, but produces a rigid hem without the roping character of a chain stitch. Most mass-market jeans are hemmed with a lock stitch.
Loom chatter — A deliberate technique in which shuttle loom tension is set lower than standard, causing the loom to vibrate as it weaves. This controlled instability amplifies the natural irregularities in the yarn — slub, nep, surface texture — producing a more characterful fabric than a normally-tensioned loom would yield. Used by Japanese mills to create highly textured denim.
Loom state — Denim fabric exactly as it comes off the shuttle loom: unwashed, unsanforized, carrying residual starch from the weaving process, covered in griège surface hairs. The starting point for all denim before any finishing. Synonymous with kibata and unsanforized. → See DU 101: What is Raw Denim?
M
Mercerization — A chemical finishing process that treats cotton with caustic soda under tension, opening the fibers and producing a rounder, shinier, more uniform surface. Used on some sanforized denim to achieve a lustrous, smooth look. Tends to reduce the surface character and texture that raw denim enthusiasts value in loom state fabric.
MIJ / MIA / MIU — Made in Japan / Made in America / Made in USA. Common abbreviations used in the community when discussing country of origin. MIJ carries particular prestige given Japan's role in preserving shuttle loom construction and developing the modern raw selvedge aesthetic.
Monozukuri — (物作り) Japanese term meaning "the art of making things." Carries a weight in Japanese culture that "manufacturing" in English does not — the idea that the act of making something with skill and care is itself meaningful, that craft is a form of integrity, and that the maker's intention lives in the finished object. A foundational philosophy of Japanese denim culture. → See DU 004: How Japan Saved Raw Denim
N
Nep — Small knots or tangles of cotton fiber visible on the surface of certain denim fabrics, caused by irregularities in the spinning process or amplified by loom chatter during weaving. Neppy denim has a distinctive textured, slightly fuzzy surface that develops interesting fades as the surface fibers wear away. → See Loom chatter, Slub
NOS (New Old Stock) — Vintage garments or fabric produced in a previous era but never sold or worn, often stored for decades. NOS raw denim — particularly vintage Levi's or Lee from the 1950s–1970s — commands significant collector prices for its historical fabric authenticity. The fabric characteristics of this period cannot be replicated in contemporary production.
O
One-wash — Unsanforized kibata denim that has been given a single controlled rinse — by the brand or the maker — before sale. Removes most initial shrinkage while preserving significantly more loom character than sanforization allows. The practical middle path between sanforized and fully unsanforized. → See DU 103: Sanforized vs. Shrink to Fit
Open-end spinning (OE) — A faster, more automated yarn spinning method introduced in the 1970s. Produces more consistent but less characterful yarn than ring spinning. OE yarn tends to hold indigo more evenly, resulting in flatter, less dramatic fades. Most mass-market denim uses OE yarn. → See Ring spinning
Osaka Five — The five Japanese denim brands that pioneered the modern raw selvedge revival beginning in the late 1970s and 1980s: Studio D'Artisan, Denime, Evisu, Full Count, and Warehouse. These brands collectively defined the aesthetic and technical standards of Japanese raw denim and laid the foundation for the global heritage denim movement. → See DU 004: How Japan Saved Raw Denim
Outseam — The seam running from the waistband to the hem along the outside of the leg. Also called the side seam. On selvedge jeans, the selvedge edge runs along the outseam — which is why the selvedge ID is visible here when the cuff is rolled. → See DU 105: The Build
Overedge stitch (Overlock) — The finishing stitch applied to the cut edges of non-selvedge fabric to prevent fraying. Its presence on the outseam indicates that the fabric was cut rather than woven to a self-finished edge. Selvedge denim does not require overlocking.
P
Patina — The accumulated visual character that develops in leather, metal, and fabric through use and age. In denim, patina refers to the overall aged appearance of a well-worn pair — fades, wear marks, hardware toning, and leather patch aging working together. A pair with good patina doesn't just look worn; it looks lived in.
Picks per minute (PPM) — The measure of loom speed — how many weft threads are inserted per minute. A shuttle loom runs at approximately 130–150 PPM. A modern projectile loom runs at 600–1,000 PPM. An air jet loom can exceed 1,500 PPM. The slower the pick rate, the lower the tension on the yarn and the more character preserved in the finished fabric. → See DU 102: What is Selvedge Denim?
Pre-distressed — Denim that has been artificially aged, faded, sandblasted, laser treated, stonewashed, or chemically processed before sale to simulate wear it hasn't experienced. The opposite of raw denim in every meaningful sense. The fades belong to nobody. → See DU 101: What is Raw Denim?
Projectile loom — The modern loom technology that replaced shuttle looms in American factories from the late 1950s onward. Fires individual weft threads across the face of the loom, cutting each at the edge and requiring an overlocked finish. Produces wider fabric at significantly higher speed. Makes wide goods rather than selvedge. → See DU 102: What is Selvedge Denim?
R
Raw denim — Denim that has not been pre-washed or artificially distressed. Comes in two forms: sanforized (pre-shrunk) and unsanforized (loom state / shrink-to-fit). Both qualify as raw as long as the fabric has not been artificially aged or distressed. The defining characteristic is that the fades belong to the wearer rather than the factory. → See DU 101: What is Raw Denim?
Raw proof — Documentation that a pair of jeans entered in a fade contest was genuinely unworn and unmodified at the start of the contest period. Typically a photograph of the jeans laid flat on the contest start date, showing unworn indigo and factory creases.
Repro (reproduction) — A modern garment made to replicate the specifications, construction methods, and fabric of a historical original — typically vintage American workwear jeans from the 1940s–1960s. Levi's Vintage Clothing (LVC) is the most prominent repro line. Japanese repro brands include Warehouse, The Real McCoy's, Sugar Cane, and Fullcount.
Right-hand twill (RHT) — The standard denim weave, in which the diagonal rib runs from bottom left to top right. Most denim in the world is right-hand twill. → See Left-hand twill
Ring spinning — The traditional yarn spinning method that twists and thins fiber into a slightly irregular, characterful yarn with natural slubs and variations. Ring-spun yarn produces more complex, more interesting fades than open-end yarn. Used in premium raw denim fabric. → See Open-end spinning, Slub
Riri — Swiss-Italian luxury zipper manufacturer founded in 1936 in Mendrisio, Canton Ticino. Considered the premium tier of zipper hardware — used by Prada, Gucci, Moncler, and Dolce & Gabbana. Characterized by exceptional smoothness, precise tolerances, and minimalist design. Appears on very high-end raw denim pieces and luxury leather goods. Often described as the Rolls-Royce of zippers. → See YKK, Talon
Rivets — Copper or brass fasteners set at the stress points of pockets. Jacob Davis's original 1873 innovation, the invention that prompted his partnership with Levi Strauss and produced the first patented pair of blue jeans. The original patent jeans also had a crotch rivet, removed after reports that it heated uncomfortably when wearers sat beside a campfire — one of the more specific problems in workwear history. → See DU 105: The Build
Rope dyeing — The premium indigo dyeing method in which yarn ends are bundled into thick ropes, passed repeatedly through indigo vats, and lifted into the air between each dip to oxidize. Produces ring-dyed yarn — indigo on the surface, white cotton core intact — which fades dramatically with wear. → See DU 101: What is Raw Denim?
Roping — The characteristic twisted, rope-like fading that develops at the hem of chain-stitched jeans as the fabric shrinks and distorts with washing. One of the most distinctive and sought-after details in raw denim. Cannot be produced by a lock stitch hem.
S
Sanforization — The mechanical pre-shrinking process patented by Sanford Lockwood Cluett in 1930, in which loom state fabric is treated with steam, passed briefly through open flame to singe surface hairs, and compressed against heated rubber cylinders to stabilize shrinkage to 1–3%. The global standard for denim finishing since the mid-twentieth century. Sanforized denim is still raw denim. → See DU 103: Sanforized vs. Shrink to Fit
Sanforized — Denim that has been through the Sanforization process — mechanically pre-shrunk at the mill before cutting and sewing. Will shrink only 1–3% after purchase. The vast majority of raw denim on the market is sanforized. Sanforized denim is still raw denim — the line between raw and non-raw is pre-washing and artificial distressing, not sanforization. → See DU 103: Sanforized vs. Shrink to Fit, Unsanforized
Sashiko — (刺し子) A Japanese embroidery and reinforcement technique using a running stitch in geometric patterns, traditionally in white thread on indigo cloth. In raw denim repair, sashiko stitching reinforces thin areas or closes blowouts while adding a distinctive visual element that makes the repair a feature rather than a correction. → See Boro, Blowout
Selvedge (selvage) — The self-finished edge of fabric produced on a shuttle loom, created by the continuous looping of the weft yarn at the edge of the fabric rather than cutting. Does not fray. Does not require overlocking. Derived from "self-edge." → See DU 102: What is Selvedge Denim?
Selvedge ID — The colored stripe woven into the self-finished edge of selvedge fabric, visible on the outseam when the cuff is rolled. Red is the most common color. Historically used by mills as a maker's mark. Still a reliable signal of selvedge construction. → See DU 102: What is Selvedge Denim?
Shank button — A button with a metal loop or shank behind it rather than holes through the face. The standard closure on quality raw denim jeans. Distributes stress more evenly across the fabric than a sew-through button, resists popping under tension, and sits flush against the waistband rather than protruding. The functional choice for workwear construction.
Shibori — (絞り) Japanese resist-dyeing technique in which fabric is bound, folded, twisted, or compressed before dyeing to create patterns where the dye cannot penetrate. One of the most refined textile arts in the Japanese indigo tradition, producing the distinctive geometric and organic patterns associated with Japanese craft dyeing. A precursor to the technical sophistication that Japanese mills later brought to selvedge denim. → See DU 001: Indigo Around the World
Shrink-to-fit (STF) — A term used interchangeably with unsanforized and kibata, describing denim that will shrink significantly — 7–10% — on first contact with water. Popularized by Levi's, who used "Shrink-to-Fit" as the product label on their unsanforized 501 jeans for decades. Buy two sizes up. Cut the inseam long. → See DU 103: Sanforized vs. Shrink to Fit, Kibata, Unsanforized
Shuttle loom — The older loom technology that produces selvedge fabric. Uses a single wooden shuttle carrying the weft yarn back and forth across the warp in a continuous loop, creating a self-finished edge at each side. Slower, narrower, and more technically demanding than a projectile loom — and produces fabric with substantially more character. → See DU 102: What is Selvedge Denim?
Singeing — The process of passing fabric quickly over an open flame or heated plates to burn away griège surface hairs without damaging the underlying yarn. Applied during sanforization and sometimes as a separate finishing step. Produces a cleaner, more uniform fabric surface. → See Griège, Sanforization
Sizing up — The practice of buying unsanforized denim in a larger size than usual to account for post-soak shrinkage. Typically one to two sizes. The golden rule: size up. An unsanforized pair that fits perfectly at purchase will not fit after the first soak. → See DU 103: Sanforized vs. Shrink to Fit
Slub — An intentional or natural irregularity in yarn thickness that produces subtle variations in the finished fabric — slight ribbing, raised texture, visual depth. A defining characteristic of ring-spun yarn woven on a shuttle loom. Slubby denim has more visual interest and typically more interesting fade potential than smooth, uniform fabric. → See Loom chatter, Ring spinning
Soak — The initial submersion of raw denim in water, either before or during first wear. For unsanforized denim, the soak induces the primary shrinkage and is essential for establishing fit. For sanforized denim, it removes residual starch and helps set initial crease patterns. Conducted in a bathtub, typically in cool or lukewarm water without detergent. → See DU 103: Sanforized vs. Shrink to Fit
Spot cleaning — The practice of cleaning specific soiled areas of raw denim without washing the full garment. Allows the wearer to maintain basic hygiene without disrupting fade development during extended dry periods.
Stacking — The bunching and folding of excess denim at the ankle when the inseam is cut longer than the leg requires. Some wearers deliberately cut their jeans long to encourage stacking. Stacks develop their own fading character — distinctive horizontal creasing at the ankle that becomes part of the garment's overall pattern.
Sukumo — (蒅) A composted indigo paste made from fermented Persicaria tinctoria leaves — the Japanese indigo plant — used in traditional Japanese aizome dyeing. Produced through a months-long fermentation and composting process, sukumo requires highly skilled vat management to achieve consistent results. The basis of the most refined Japanese natural indigo dyeing tradition. → See Aizome, DU 001: Indigo Around the World
Sulfur dyeing — A dyeing method using sulfur-based dyes, most commonly applied to produce black denim or darker base tones. Sulfur dyes bind more strongly to fiber than indigo and are significantly more resistant to fading. Black raw denim is almost always sulfur-dyed.
T
Talon — The world's first zipper manufacturer, founded in 1893 as the Hookless Fastener Company and renamed Talon in 1928. The dominant zipper brand in America through World War II. Vintage Talon zippers — particularly the distinctive pulls found on original Levi's 501s from the 1940s and 1950s — are one of the details vintage denim collectors examine closely when authenticating pieces. Still manufacturing today; used by Levi's, Brooks Brothers, and Uniqlo among others. → See YKK, Riri
Tate-ochi — (縦落ち) Japanese term for the vertical fading pattern that develops on the face of denim, particularly in slubby or heavily textured fabric. The irregular yarn thickness causes the indigo to wear away faster on the raised portions of the weave, creating dramatic vertical striping as the white cotton core is revealed. Tate-ochi is one of the most sought-after fade effects in Japanese denim culture and is strongly associated with shuttle loom construction and ring-spun yarn.
Top block — The upper portion of the jean — from the waistband through the seat and upper thigh. The most critical and most difficult dimension to fit correctly, particularly in ready-to-wear. A well-fitting top block is the foundation of a pair of jeans that works. Everything else is comparatively easy to adjust.
Train tracks — The parallel fade lines that develop along the outseam of selvedge jeans as the raised seam rubs against surfaces during wear. Named for their visual resemblance to railway tracks. A signature detail of selvedge construction.
3×1 twill — The weave structure that defines denim: three warp threads pass over one weft thread in a repeating diagonal pattern, offset by one thread per row. The "3×1" describes the ratio of over-to-under — three over, one under. This structure produces the characteristic diagonal rib visible on the face of any pair of jeans, and gives denim its distinct dark face and lighter reverse (since the indigo-dyed warp dominates the face while the white weft shows on the reverse). Fabrics below 10.5oz typically use a 2×1 weave instead. → See Cotton twill, Warp, Weft
U
Unsanforized — Denim that has not been through the sanforization process. Synonymous with loom state, shrink-to-fit, and kibata. Retains the full loom character of the fabric — griège surface hairs, natural irregularities, uncompromised texture. Shrinks 7–10% on first contact with water. Both unsanforized and sanforized denim are raw denim — the distinction is about shrinkage management, not authenticity. → See DU 103: Sanforized vs. Shrink to Fit, Kibata, Shrink-to-fit
W
Wabi-sabi — (侘び寂び) Japanese aesthetic philosophy finding beauty in imperfection, impermanence, and incompleteness. In the context of raw denim, wabi-sabi is the philosophical framework behind the entire fade culture: a pair of jeans is not finished when you buy it, it is improved by use, imperfection, and time. The fades, the repairs, the wear marks — these are not flaws but expressions of authenticity. → See DU 004: How Japan Saved Raw Denim
Wallet fade — The rectangular impression left on the back pocket by a wallet carried consistently in the same pocket. A personalized fade specific to the individual wearer — the size, shape, and position of the wallet fade records a specific habit of a specific person.
Warp — The vertical threads in a woven fabric — the threads that run the length of the fabric on the loom. In denim, the warp threads are indigo-dyed. The warp carries the color and determines how the fabric fades over time. → See Weft, 3×1 twill
Wash — The deliberate introduction of water and detergent to clean raw denim. The most contested topic in the raw denim community — some enthusiasts wash rarely or never to maximize fade contrast; others wash regularly to extend fabric life and prevent blowouts. The honest answer: regular washing, inside out, in cold water with a gentle detergent, extends the life of the garment without meaningfully compromising the fades. The jeans will thank you.
WAYWT (What Are You Wearing Today) — A recurring thread format on r/rawdenim and other communities in which members post outfit photos including fade progress on their jeans. A major source of community fade documentation and style reference. One of the oldest recurring formats on the subreddit.
Weft — The horizontal threads in a woven fabric — the threads that travel across the width of the loom with each pass of the shuttle. In denim, the weft is typically undyed white cotton. The weft is what creates the selvedge edge as the shuttle loops back at each side. → See Warp, 3×1 twill
Whiskers — The horizontal and diagonal crease fades that develop at the hip and upper thigh area, radiating outward from the crotch. Named for their resemblance to cat's whiskers. Also called hige (ヒゲ) in Japanese. Among the first fades to develop on a new pair of raw denim and among the most celebrated — the visible record of how a person stands, sits, and moves.
Wide goods — Non-selvedge denim woven on a projectile loom, typically 60 inches wide rather than the approximately 30 inches of selvedge fabric. Not inherently inferior, but generally associated with less surface character and fade potential than shuttle loom construction. → See DU 102: What is Selvedge Denim?
Y
YKK — Yoshida Kogyo Kabushikikaisha (Japan, founded 1934). The world's largest zipper manufacturer, producing approximately half of all zippers globally. The industry standard for quality and reliability in denim. Their Excella line is their premium metal zipper, found on higher-end zip-fly jeans and luxury goods. The YKK initials stamped on the pull are a genuine signal of quality control. Named for founder Tadao Yoshida. → See Talon, Riri
Yoke — The horizontal back panel of a pair of jeans running from side seam to side seam, sitting below the waistband and above the seat. Most wearers read it as a decorative detail. It is structural. The yoke is a slashed dart — a tailoring technique for giving flat fabric three-dimensional shape — exploded into its own pattern piece. The angle and depth of the yoke determines the shape of the seat. It is what makes a jean a jean. → See DU 105: The Build
What Comes Next
That's the 100 level — the foundational vocabulary of raw denim. You now know what raw denim is, how selvedge is woven, how to manage shrinkage, how to think about weight, what every part of the garment is called, and the language the community speaks. The 200 level is where the practical business begins: how to buy, how to fit, and how much to spend.
← Previous: DU 105 — The Build: Every Part of a Jean, Explained | Next: DU 201 — How to Buy Your First Pair of Raw Denim Jeans →
Eric Steffen is the founder of FITTED Underground, a custom jeans and raw denim workshop at 108 Bayard Street in Williamsburg, Brooklyn. He has been making jeans by hand since 2014. Denim University is his attempt to share everything he's learned — about the history, the craft, and the culture behind the world's most enduring garment.
